Blue Security (site's down), the anti-spam service run by former Russian spammers, is a favorite spammer target due to its ruthless de facto DDOS attacks on spam senders. (This tactic recently earned it some revenge spam from a spammer who checked their mailing list against Blue Frog's public e-mail list and targeted the overlap.)
This week, Blue Security fought off a DDOS attack by pointing bluesecurity.com not to its main site, but to its Typepad-hosted blog at bluesecurity.blogs.com, according to Q Daily News. As a result, Typepad and LiveJournal (both owned and hosted by Six Apart) went down for four hours, according to QDN. Six Apart has graciously called all this a "sophisticated denial-of-service attack" and not "Blue Security fucking up again."
But maybe Six Apart has nothing to gloss over. Some commenters at QDN contend that the attack looked more like a direct DDOS on Six Apart's servers, which happened to coincide with an attack on Blue Security.
The lesson learned: Forget ethical reason, spammer hatred alone makes business with Blue Security too risky to bother with.